Sylvia, now 82, was diagnosed with Alzheimer's at the end of 2016. A few months later, she was put into hospital after a fall resulting from an epileptic seizure – a side effect Epilepsy Research UK reports is often linked to the disease.

During this period, Sylvia's dementia became so bad that she accused hospital staff of kidnapping her, Mark recalled. She no longer recognised him at all, a time he described as "the lowest point in his life".

He and Sylvia had always been close, especially since the deaths of Mark's father and brother years earlier.

"We are not just a mother and son, but a brother and sister, best friends, soul mates," he wrote in a blog for UK charity Alzheimer's Society.

He resolved to take action.

"It was no quick fix," Mark explained on the blog.

Together with Sylvia's treatment team, he planned out "a healthy diet with gentle physical and cognitive exercises". (The Society shared Sylvia's personal plan in Mark's blog post – which had a focus on "brain-nourishing" foods such as berries and leafy greens – and encourages anyone with the condition to consider these steps.)